The following paragraph has one local leader complaining that Tarquin has called the gathering but hasn't showed up.. so what does ipse Tarquinius paulo antequam sol occideret venit! suggest? That he arrived the previous night befor sunset?... And if he's not there during the gathering then where is he...?

1) Peregrinus is an adjective here. Peregrinis opibus "by foreign resources/by external help/power, etc", meaning that his close links with the Latins will protect him from unrest at home (inter cives).

2) paulo antequam sol occideret "not long before the sun set". All the others were there at dawn (prima luce) but Tarquin, in sharp contrast (cf. ipse) arrives only at the end of the day.